Molar Pregnancy

A form of gestational trophoblastic disease.

Complete mole (46XX, entirely paternal genetic origin, no fetal tissue, diffuse trophoblastic hyperplasia) carries a higher risk of progression to persistent gestational trophoblastic disease or choriocarcinoma (roughly 15 to 20%) than partial mole (69XXY triploid, fetal tissue present, focal hyperplasia, risk roughly 0.5 to 1%).

Vaginal bleeding, hyperemesis (driven by markedly elevated hCG), a uterus large for dates, early pre-eclampsia (before 20 weeks should always prompt consideration of molar pregnancy), biochemical hyperthyroidism (hCG cross-reacts with the TSH receptor), and, classically, passage of grape-like vesicles.

Theca lutein ovarian cysts are common on ultrasound.

Ultrasound shows a characteristic "snowstorm" appearance in complete mole.

Serum beta-hCG is typically markedly elevated, often above 100,000 IU/L.

Histology of evacuated tissue confirms the diagnosis and subtype.

• Suction curettage (evacuation) is the treatment of choice regardless of uterine size; oxytocics are generally avoided or used cautiously until evacuation is complete

• Anti-D prophylaxis for Rh negative women

• Serial serum beta-hCG monitoring post-evacuation until three consecutive normal weekly results, then monthly for 6 months for complete mole (shorter follow up for partial mole per local protocol), with registration at a specialist gestational trophoblastic disease center

• Effective contraception during follow up to avoid confounding hCG monitoring, barrier methods or combined oral contraceptive once hCG has normalized; intrauterine devices avoided until hCG is normal

• Persistent gestational trophoblastic disease or choriocarcinoma: methotrexate-based chemotherapy for low risk disease per FIGO scoring, or combination chemotherapy (commonly the EMA-CO regimen: etoposide, methotrexate, actinomycin D, cyclophosphamide, vincristine) for high risk disease

Referral: specialist gestational trophoblastic disease center for all confirmed molar pregnancies.